They require a deployment connection.
They can be used only between related organisation.
They use an all or non deployment model.
They can be used to transfer contact records.
They can be used to deploy custom settings data.
ChangeSet question - Salesforce Developer Community developer.salesforce.com > forums
For more information, see Quick Deployments. A change set is deployed in a single transaction. If the deployment is unable to complete for any reason, the entire transaction is rolled back. After a deployment completes successfully, all changes are committed to your org and the deployment can't be rolled back.
Deploy a Change Set - Salesforce Help
help.salesforce.com > apex > HTViewHelpDoc > id=sf.changesets_inbound...
Use change sets to send customizations from one Salesforce org to another. For example, you can create and test a new object in a sandbox org, then send it to your production org using a change set. Change sets can contain only modifications you can make through the Setup menu.
Change Sets - Salesforce Help
help.salesforce.com > articleView > id=changesets.htm
Complete the deployment in your target production organization
1. Login to the target organization.
2. Navigate to Setup and enter Change Set into the Quick Find box.
3. Click Inbound Change Sets.
4. Under "Change Sets Awaiting Deployment," click your Change Set's name.
5. Click Validate to validate the components. ...
6. Click Deploy.
Deploy change sets from sandbox to production - Salesforce Help help.salesforce.com > HTViewSolution